Batch Chunk Simple

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How to run the sample
The source code for this sample can be found in the javaee7-samples GitHub repository. The first thing we need to do is to get the source by downloading the repository and then go into the samples folder:
git clone git://github.com/javaee-samples/javaee7-samples.git
cd javaee7-samples/batch/chunk-simple/
Now we are ready to start testing. You can run all the tests in this sample by executing:
mvn test
Or you can run individual tests by executing one of the following:
mvn test -Dtest=ChunkSimpleTest

Chunk Processing - Read, Process, Write

ChunkSimpleTest

The Batch specification provides a Chunk Oriented processing style. This style is defined by enclosing into a transaction a set of reads, process and write operations via ItemReader, ItemProcessor and ItemWriter. Items are read one at a time, processed and aggregated. The transaction is then committed when the defined checkpoint-policy is triggered.

<?xml version="1.0" encoding="UTF-8"?>
<job id="myJob" xmlns="http://xmlns.jcp.org/xml/ns/javaee" version="1.0">
    <step id="myStep" >
        <chunk item-count="3">
            <reader ref="myItemReader"/>
            <processor ref="myItemProcessor"/>
            <writer ref="myItemWriter"/>
        </chunk>
    </step>
</job>

A very simple job is defined in the myJob.xml file. Just a single step with a reader, a processor and a writer.

We’re just going to deploy the application as a web archive. Note the inclusion of the following files:

/META-INF/batch-jobs/myJob.xml

The myJob.xml file is needed for running the batch definition.

@Deployment
public static WebArchive createDeployment() {
    WebArchive war = ShrinkWrap.create(WebArchive.class)
            .addClass(BatchTestHelper.class)
            .addPackage("org.javaee7.batch.chunk.simple")
            .addAsWebInfResource(EmptyAsset.INSTANCE, ArchivePaths.create("beans.xml"))
            .addAsResource("META-INF/batch-jobs/myJob.xml");
    System.out.println(war.toString(true));
    return war;
}

In the test, we’re just going to invoke the batch execution and wait for completion. To validate the test expected behaviour we need to query the Metric object available in the step execution.

The batch process itself will read and process 10 elements from numbers 1 to 10, but only write the odd elements. Commits are executed after 3 elements are read.

@Test
public void testChunkSimple() throws Exception {
    JobOperator jobOperator = BatchRuntime.getJobOperator();
    Long executionId = jobOperator.start("myJob", new Properties());
    JobExecution jobExecution = jobOperator.getJobExecution(executionId);

    jobExecution = BatchTestHelper.keepTestAlive(jobExecution);

    List<StepExecution> stepExecutions = jobOperator.getStepExecutions(executionId);
    for (StepExecution stepExecution : stepExecutions) {
        if (stepExecution.getStepName().equals("myStep")) {
            Map<Metric.MetricType, Long> metricsMap = BatchTestHelper.getMetricsMap(stepExecution.getMetrics());

            (1)
            assertEquals(10L, metricsMap.get(Metric.MetricType.READ_COUNT).longValue());
            (2)
            assertEquals(10L / 2L, metricsMap.get(Metric.MetricType.WRITE_COUNT).longValue());
            (3)
            assertEquals(10L / 3 + (10L % 3 > 0 ? 1 : 0),
                         metricsMap.get(Metric.MetricType.COMMIT_COUNT).longValue());
        }
    }

    (4)
    assertEquals(jobExecution.getBatchStatus(), BatchStatus.COMPLETED);
}
  1. The read count should be 10 elements. Check MyItemReader.

  2. The write count should be 5. Only half of the elements read are processed to be written.

  3. The commit count should be 4. Checkpoint is on every 3rd read, 4 commits for read elements.

  4. Job should be completed.

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Recent Changelog

  • Dec 14, 2014: Switch from polling on jobexecution (for job completion) to polling with joboperator and executionid by Scott Kurz
  • Jul 05, 2014: Removed header license for batch xml files by Roberto Cortez
  • Jun 22, 2014: Removed header license. the licensing is now referenced in the license file in the root of the project by Roberto Cortez
  • Jun 20, 2014: Added fqn to java ee api references to generate direct links to javadocs by radcortez
  • Jun 19, 2014: Documentation clarifications and typos by radcortez
  • Jun 18, 2014: Fixed documentation of chunk-simple project by radcortez
  • Jun 18, 2014: Added documentation to chunk-simple project by radcortez
  • Dec 31, 2013: Code style issues by Roberto Cortez
  • Dec 31, 2013: Removed servlets and jsp's by Roberto Cortez
  • Nov 21, 2013: Moved batch-utils project one level up and renamed it to utils by Roberto Cortez
How to help improve this sample
The source code for this sample can be found in the javaee7-samples GitHub repository. The first thing you need to do is to get the source by downloading the repository and then go into the samples folder:
git clone git://github.com/javaee-samples/javaee7-samples.git
cd javaee7-samples/batch/chunk-simple/

Do the changes as you see fit and send a pull request!

Good Luck!